There have been known variable valve operating apparatuses for use in internal combustion engines, including a cam switching mechanism in which a cam carrier has a plurality of cam lobes formed on the outer circumferential surface thereof and having different cam profiles that determine valve operating characteristics. The cam carrier is relatively non-rotatably and axially slidably fitted over a camshaft, and is axially moved to cause different cam lobes to act on engine valves to switch the valve operating characteristics (see, for example, Patent Document 1).